How many valence electrons are present in the element of third period and third group?

The elements of the second period of the periodic table are given below :

$\mathrm{Li}, \mathrm{Be}, \mathrm{B}, \mathrm{C}, \mathrm{N}, \mathrm{O}, \mathrm{F}$
(a) Give reasons to explain why atomic radius decreases from $\mathrm{Li}$ to $\mathrm{F}$.
(b) Identify the most (i) metallic and (ii) non-metallic element.

An element E has the following electronic configuration :

(a) To which group of the periodic table does element E belong?
(b) To which period of the periodic table does element E belong?
(c) State the number of valence electrons present in element E.
(d) State the valency of the element E.